Remove second commit; add docs to .git-blame-ignore-revs

Author: anoadragon453

.git-blame-ignore-revs

@@ -1,6 +1,13 @@
+# Commits in this file will be removed from GitHub blame results.
+#
+# To use this file locally, use:
+#   git blame --ignore-revs-file="path/to/.git-blame-ignore-revs" <files>
+#
+# If ignoring a pull request that was not squash merged, only the merge
+# commit needs to be put here. Child commits will be resolved from it.
+
 # Run black (#3679).
 8b3d9b6b199abb87246f982d5db356f1966db925
-a001038b92c4f0082cad60e5e87d0bd01374c9de
 
 # Black reformatting (#5482).
 32e7c9e7f20b57dd081023ac42d6931a8da9b3a3